FIG. 1 illustrates a conventional computer tomography (“CT”) scanner 100. CT scanner 100 includes an x-ray source mounted on a movable ring, gantry 22. Gantry 22 includes an array of x-ray detectors mounted opposite the x-ray source. A patient lies on a cradle 30 that moves through gantry 22. Cradle 30 is supported by stationary imaging platform 40. Gantry 22 is rotated so that the x-ray source and detectors revolve around the patient, while the patient is moving through gantry 22 on cradle 30. Each rotation of gantry 22 generates a two-dimensional x-ray slice of the patient. As the patient moves through gantry 22 the x-ray slice images are stored. The x-ray slices are combined together to form three-dimensional images of the patient and/or a particular organ of the patient.
The top surface of cradle 30 has a semi-tubular shape. In some situations, it is desirable to have a patient lying on a flat surface rather than a semi-tubular surface. FIG. 2 illustrates an overlay 50 designed to lay on a cradle 30. Overlay 50 has a flat upper surface and thus provides a flat upper surface for a patient to lie on. Overlay 50 moves with cradle 30 as cradle 30 moves in and out of gantry 22. Often, stationary imaging platform 40 will include a fixed shroud 45. A problem arises when overlay 50 is placed on cradle 30, a pinch point is formed between overlay 50 and fixed shroud 45. It is possible that a patient's fingers could get caught between the underside of the overlay 50 and fixed shroud 45 as overlay 50 is moving in or out of gantry 22.
FIG. 3 illustrates one approach to solving this problem. Foam strips 60 are placed lengthwise along the underside of overlay 50 adjacent the edges to reduce the space between fixed shroud 45 and overlay 50. The reduction in space is designed to prevent objects from becoming pinched between fixed shroud 45 and overlay 50. One problem with this approach is that foam is not very resilient. The foam can be easily torn, distorted, or lose its adhesion to overlay 50. An additional problem with this approach is that the foam is difficult to clean. Often during a CT scan a variety of fluids may be present. For example, a patient may be receiving intravenous fluids. Or, a patient may be receiving iodine or a radioactive dye to assist with imaging during the CT scan. These fluids could be spilled on overlay 50, and therefore on foam strips 60. Additionally, even if no external fluids are present, an ill patient may vomit or urinate during the CT scan. Foam strips 60 would absorb these fluids. It is difficult to sufficiently sterilize foam strips 60.
What is needed is a different solution to address the pinch point that forms between fixed shroud 45 and overlay 50.